Spectral and timing evolution of the black hole transient MAXI J1727-203 with NICER

MAXI J1727-203 is a new X-ray transient discovered on 5 June 2018. A hard-to-soft state transition at the beginning of the outburst led to the identification as a black hole candidate. MAXI J1727-203 was monitored with the Neutron Star Interior Composition Explorer (NICER) on an almost daily basis from the beginning of the outburst. We present a spectral and timing analysis of the full outburst of the source, which lasted approximately four months. A preliminary spectral analysis suggest that the accretion disk component can was detected throughout the entire outburst, with temperatures ranging from ~0.4 keV (in the soft state), down to ~0.2 keV near the end of the outburst when the source was in the hard state. The power spectrum in the hard state shows broadband noise up to 10 Hz, with no detection of any quasi-periodic oscillations. We argue that the system's characteristics are not consistent with those expected for a neutron star and that they are particularly reminiscent of the black hole X-ray binaries XTE J1118+480 and Cyg X-1.